This invention relates to centrifuge rotors and, more particularly, to a centrifuge rotor having swinging members whose pivot point shifts during operation to facilitate operation.
One of the many application of centrifuges is that of processing biological substances. According to usual practice, these biological substances are placed in a swinging bucket or swinging carriers holding test tubes. The substances are then subjected to centrifugal force by the centrifuge. During this operation the swinging buckets swing outwardly and the heavier components of the substance are driven to the bottom of the test tubes. Following this the rotor is stopped, allowing the tubes to swing back down to the vertical position. They are locked in this position and the centrifuge again operated such that the top portion of the contents of the bucket become decanted. Additional washing or other liquids are supplied to the tubes typically during the time that they are in the horizontal spinning position.
A cell washing centrifuge apparatus for processing substances in this manner is described, for example, in U.S. Pat. No. 3,420,437 issued Jan. 7, 1969 to Josef Blum. As is described in the said Blum patent, because of the manner in which the tubes are hinged to the rotor -- off center of the longitudinal axis of the tubes -- they hang normally at a slight negative angle relative to the vertical axis of the rotor, such that they are easily locked in position to effect positive as well as negative angle decanting.
Unfortunately one of the problems encountered with a system of this type, is caused by the fact that the hinge or pivot point of the tube is off center from the longitudinal axis of the tube. Hence, the tubes are not quite able to assume a true horizontal position during spinning. With the tubes in a generally horizontal position, their hinge point is below their center of gravity and the resulting lever arm between the hinge point and the center of gravity or the axis of the tube forces the tubes downwardly somewhat. Because the tubes are unable to assume a true horizontal position, the resulting separation is not quite as perfect as would otherwise be desired.
It is therefore an object of this invention to obviate many of the disadvantages of the prior art swinging member centrifuges.
An additional object of this invention is to provide an improved centrifuge rotor whose swinging members have a shifting pivot point which shifts to improve operation.
A further object of this invention is to provide an improved centrifuge rotor whose swinging members are able to swing to a true horizontal position during operation.